Variable condenser



May 1927. 1,630,885

J. R. BAR NHART VARIABLE CONDENSER Filed April- 9. 1524 Patented May 31, 1927.

UNITED STATES 1,630,885 PATENT OFFICE."

JOB R. BARNHART, F LAKEWOOD, OHIO, ASSIGNOR T0 WALTER M. sco'r'r, OF LAKE- WOOD, OHIO.

VARIABLE Application filed Aprils,

This invention relates to variable condensers for use in radio circuitsand has for its primary object toiprovide a particularly efiicient form of" variable condenser which sha'll be simple inl'constrliction. andinexthe desire d capacity value the elements constituting the ,condense ,being so arranged sha th tl eire aediiet eere ma ntaine e i h h ev" i e i' s te tto ver s-f "'T-IYY'. ,zi i. I I twithithese ana .eth fibie si ei i w, h en iee. 9 l%n ith r isiae tures pfco'nst uction arrangement or combination, allof .which ,wiill be fully des r ied her z ette aend. Poin d t u nt flppe del s msi it In the nying.fl w esetei'le ng r rtae thispe wtienaltia We p view, with parts broken away, of a condenser constructed in accordance with my invention and igs.12 and 3 are respectively enlarged longitudinal and transverse sec tional views taken on the lines 2-2 and 3-3 of Fig. 1.

Describing the various parts by reference characters, 1 denotes the base which is shown as rectangular in shape and which is made from bakelite, hard rubber, or other suitable insulating material. Secured adjacent each end of the base by means of an eyelet 2 is a metal conductor plate 3 having a downturned portion 4 which is adapted to engage the end of the base to prevent rotation of said plates about their respective eyelets. These conductor plates project toward, but are separated from, each other, as shown in Fig. l, and each plate is formed with converging sides 5 which terminate in an arcuate shaped end 6.

Located between the base 1 and each metal plate is a spacing strip 7 and a sheet of dielectric material 8. The spacing strips 7 may be formed from any suitable material CONDENSER.

1924. Serial No. 705,181.

and serve to space the sheet of dielectric material 8 a slight distance from the base 1, as shown in .Fig. 2- The sheet of dielectric material maybe formed from mica or other suitable material and is preferably of the samesize'as the base 1 and is provided with an aperture at substantially the midpoint thereof. A rotatable conductor element is interposed between the base and the dielectric sheet 8. madefrom sheet metal and:is. formed with anembossed hub portionflOand oppositely extending vanes 11. The hub 10 is adapted to project .up through. the'aperturein the dielectric 8, as shown in Fig. 2, and. a slot 1 2 is formed therein to facilitate the adjustment of the device. I

,In .use, the. condense1',may beconnected in the circuit by soldering the. connecting wires directly to the, metal plates 3, .or ,estab- ,lishing a connection with screws or bolts (ubtshown) inserted}.thifougli ieygelets 2,1 in any. other. suitable, manner. The capacity of the condenser may be .varied by rotati ng i n en t, it being. understood tliat inaxim um .capacity i s'obtained when the vanes 1 l.,are a t-neatl b le lil h p a el-t t s -.m. mi Q Pa WH Q iQed wh n-t vanes 1 ,flgie midway between theend plates, ,as shown in 1g. ,and full lines. .The eqs fiiee i; h o ata le. lem nt indicated in] dash ne t eithis fis relindi e e I justment substantially midway between minimum and maximum capacity.

The device is relatively small and compact and is readily connected in the circuit and is light enough to be supported by the connecting wires. The capacity may be easily varied by inserting the blade of a screw driver in the slotted hub 12 and the light tension in the dielectric sheet 8 on the movable element is sufiicient to retain the desired adjustment even against severe shocks.

Having thus described my invention, what I claim is:

1. A variable condenser of the character set forth comprising a base of insulating material, a spacing element located adjacent each end of said base, a sheet of dielectric material positioned on said elements, a conductor plate located adjacent each end of said base, an eyelet securing each conductor plate and spacing element and di- This element is preferably [the hub 101 of. the. movable conductor ele-,.

electric =sheetjito"; said base, said dielectric sheetbein'g-provided with an aperture intermediate said conductor plates, and a conductor -elemen :-in erposed wbeta. am s id; base and dielectric sheet and having a portion projecting through the aperture in said dielectric, said conductor elementbeingirotatable about the axis of such projecting portion to vary the position of-said *lcnie'nt' .with respect to said conductor plates.

'2. A variable condenscr ofthe character s et"forth comprising a base of insulating material, a sheet 'of -dielectric material Inounted on said base, spaced conductor jplates on said 'base and overlapping said dielectric material, said dielectric 'material being'provided with an aperture intermediate said plates," and a conductor element interposed between said dielectric sheet and 3. A Va riab'le cond ii's'er o f -the""character set forth compris ng'fafbase of insulating matenal, a sheet of dielectric material secured to wasps-carriers "sqiabas andfhavingfan aperture in "'the; ientral.' portion thereof, a

wages-admires eg vakyehe' sesame-ea: said francs-With res E material, a sheet of dielectric; material mounted on said base, 'spaced conductor plates secured to said base and overlying said/d ielectric sheet, means fo r fiasteningsaid inlatcs and dielectric sheet to said base said sheet of dielectric n'iaterial having an aper :tu-re therein, a conductor clement rotatably mounted on said base and having a portion 'thereof projecting' through said aperture whereby said conductor element may be rotated to vary the capacity of said condenser. 5. A variable condenser of the character set forth comprising a base of insulating material, spacing strips on said base and a sheet of dielectric material mounted on said spacing strips, spaced conductor plates secured to said base andv overlapping saiddielectric sheet, said dielect-ric'she'et having an aperture "therein intermediate said conductor plates, a conductor element'interposed between said dielectricsheetand'base, said conductor element having a part projecting through said aperture and adapted 'tobe rotated to vary'th'e positionjthereof with 'respect'to said conductor plates.

6. A variable condenserof the character set forth comprising abase of insulating m'at-erial, a sheet of dielectric material-secured to said base, a' pairof spaced conductor plates secured to said base and overlapping said dielectric sheet; said dielectric,'sheet having an opening therein interm ediatefsaid conductor plates, a {rotatable conductor" element j'ournaled in said opening aiid "having oppositely disposedvanesthereonpiojecting between said dielectric sheet atid ba seg jsaid vanes adaptedto 'befrictionallyjheild jb'etween said dielectric sheet and base when set' in a predeteriiiinedpositionj -1 In:testimony'whereoffI hereunto afli'x' iny' si'gnature. 7- 

